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Supplement warning: Probiotics work by replacing "bad" bacteria in the gut with "good" bacteria

Research has found probiotics can be useful for treating symptoms of IBS. But other studies have found they make little difference to gut health.

Taking probiotic supplements has also become popular in recent years.

Research by the University of Chicago has found probiotics can be useful for treating symptoms of IBS, such as bloating and abdominal pain.

However, scientists are now questioning whether probiotics are as effective as previously thought.

"Thirty billion Lactobacillus sounds good, but after going through the stomach acid, only about 43 of them survive," said Ian Orme, a professor of microbiology and pathology at Colorado State University, to Business Insider.